The present invention concerns a method of preparing foam or froth from a milk-based alimentary liquid, intended for example, to be used in the preparation of coffee-based drinks such as cappuccinos, milky coffee, café latte and macchiato, etc. The present invention also concerns a device for implementing said preparation method.
Currently, the most common method of preparing foam from a liquid such as milk is to pour the desired quantity of milk into a receptacle, to dip the steam outlet nozzle of a coffee machine into the receptacle while shaking it from top to bottom to draw in the air necessary to obtain foam.
A first drawback of this method is the need to have either a professional type coffee machine which is generally expensive, or a domestic coffee machine with a steam outlet nozzle which is generally inappropriate.
Another drawback lies in the fact that it is not generally possible to prepare the foam at the same time as the coffee, unless one has a complex and expensive coffee machine with fluid systems for producing hot water for the coffee and for producing steam that are independent of each other.
Another drawback linked to the use of coffee machines with a steam outlet nozzle arises from the fact that the water heating system in such machines, usually a heating-unit, has to remain permanently switched on in order to be kept at a high temperature and to be able to produce steam without requiring inconvenient waiting time. These coffee machines consequently consume significant quantities of energy, which makes the use thereof uneconomical. It should also be noted that depending upon the hardness of the water used, the steam flow nozzles quickly become coated with limescale so that the machines have to be regularly taken out of service in order to descale them.
Another drawback of this type of machine arises from the fact that the quality of the foam obtained depends upon the skill of the user such that the machines do not allow foam with homogenous consistence and quality to be obtained in a reproducible manner.
Household appliances for stirring alimentary liquid in order to generate foam using mechanical elements are already known. However, the operation mode of these devices is too general and not adapted for generating a smooth, fine and hot milk foam in a very short period of time in order to prepare a drink such as a cappuccino. The use of these devices is also not very practical or very hygienic. Indeed, the stirring elements need to removed to be cleaned which requires some handling by the user. The stirring elements can also dirty the rest of the device when it is dismantled particularly the heating element with all the drawbacks linked with cleaning burnt on food residue. All these drawbacks make them inconvenient to use for preparing foam based drinks.